package com.dyz.leetcode._12_linkedList;

import com.dyz.leetcode.ListNode;

public class _23_mergeKLists {
    public ListNode mergeKLists(ListNode[] lists) {
        if(lists==null||lists.length==0){return null;}
        ListNode outputlist = lists[0];
        for(int i=1; i<lists.length; i++){
            outputlist = mergeTwoLists(outputlist, lists[i]);
        }
        return outputlist;

    }
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        if(list1==null){
            return list2;
        }
        if(list2==null){
            return list1;
        }
        ListNode l1 = list1;
        ListNode l2 =list2;

        ListNode dummy = new ListNode(-1);
        ListNode curr = dummy;

        while (l1!=null &&l2!=null){
            if(l1.val<l2.val){
                curr.next = l1;
                l1 = l1.next;
            }else {
                curr.next = l2;
                l2 = l2.next;
            }
            curr = curr.next;
        }
        if(l1==null){curr.next = l2;}
        if(l2==null){curr.next = l1;}
        return dummy.next;
    }
}
